The HSDRC Transgenic Models of Skin Disease Core has been successful in integrating transgenic technology into the study of the pathogenesis of skin diseases, making transgenic approaches easily accessible to investigators requesting its services. The technical and intellectual expertise of the Transgenic Models Core have been instrumental in generating valuable mice strains for the projects of over 60 investigators, facilitating the generation of over 100 novel mouse strains. The Transgenic Models Core has offered the following services: generation of transgenic mice by pronuclear injection of DNA constructs, production of targeted embryonic stem (ES) cell lines by electroporation of gene targeting vectors, and microinjection of targeted ES cells into blastocysts for the generation of knockout mouse strains. The transgenic core also has provided advice and training in transgenic technology, ES cell culture techniques, and animal husbandry needed for the establishment and maintenance of transgenic strains. The Transgenic Models Core has facilitated P&F studies and has provided an important method for publicizing the HSDRC and led to the recruitment of new investigators to the HSDRC. A transgenic and knockout database has been developed by the Core to describe transgenic and knockout mouse strains which are available for skin disease research. The considerable expense and training time needed to independently execute transgenic approaches represents a barrier for many investigators that the Transgenic Models Core is able to overcome. The heavy use of this Core demonstrates the continued need for these services. Funds from the Core were used to amplify microinjection services provided by the BWH Core Transgenic Mouse facility, enabling an increase in productivity of the core by 20%. Funds were also used to subsidize the costs of ES cell culture, with a 50-50 cost sharing between the investigator requesting services and the Core. The Core will continue to provide services to assist investigators with the generation of transgenic and knockout mice. The core will also continue to incorporate conditional transgenic and knockout approaches for the study of skin disease. Significantly, these technologies provide investigators with new methods to focus on skin prospectively through the generation of tissue and temporal specific transgenic and knockout mice.